Worlds Collide
by IWriteFanfictionBecauseOfEggs
Summary: When the Young Justice team get news that a portal opened up, throwing out four people who begin fighting what will they do? And then to learn that one of them is also a Robin? What is going on? Can the Young Justice team help the Teen Titans get back home? Or will they be stuck there forever? Main ships: Chalant, Spitfire (YJ) Robstar (TT) Rated T for language
1. Chapter 1

**Reminder: THEY ARE IN DIFFERENT EARTHS (Plus I haven't seen Teen Titans in A WHILE so sorry if they are a bit OOC)**

 **Disclaimer: I own nothing!**

 _ **Author's P.O.V.**_

They had saved the Justice League last week from Vandal Savage. They were given a small break. And throughout that time many things happened. New relationships were formed and Robin had revealed his identity. They were now all sitting down, on the couches Zatanna and Robin sitting next to each other both awkwardly trying to find a comfortable position and not trying to embarrass each other. While Artemis had her head on Wally's chest and Megan was sitting in Conners lap. Kaldur was back in Atlantis and Raquel was back in her home. It was relaxing, nothing out of the ordinary has yet to happen.

Dick pressed his finger to his year talking to whoever was talking to him. "Got it." he finished and he stood up. "There was this portal just a few blocks from here...these, people came out and they are fighting one another." he quickly filled them in. Wally sped into his costume and Zatanna chanted a spell. Conner was already wearing his and M'gann morphed into hers. Dick gave Artemis a look of sympathy and shrugged before Zatanna breathed out a laugh and cast another spell, changing the two of them into their costumes.

"I don't think I'll ever get used to that."

* * *

"Give it up Slade!" Robin yelled out. **(Just for the sake of less confusion I'm going to call YJ Robin's Rob/Dick and TT's Robin...Robin. Got it?)** Starfire used her laser eyes to try and get him, but they never even got close to him. Instead, they destroyed the street below her. Beastboy transformed into a Gorilla and chased the villain, to no luck, and was easily hit and taken to the ground. Robin was instantly regretting having Raven and Cyborg stay at the Tower.

Slade laughed and shook his head "You can't win against me Robin, admit it." he laughed approaching the boy. But soon the villain felt a weight on his shoulders and was swiftly turned around and on his stomach. Laying on the floor. Once the weight was lifted her stood up instantly and narrowed his eye. "Another Robin? Interesting." smoke took over their sight and Slade was gone.

Starfire and Beastboy were approaching the still alarmed team. Conner was approaching Starfire with anger and threw his fist at her, she caught it quickly with surprising strength for her slim stature. That though didn't stop him from swinging a fist to the side of her stomach her face twisted at the newfound pain as she was now getting up from the ground.

The two Robin's looked at each other, studying one another. one had brighter clothing while the other had darker. Robin was the first to make a move while Rob just blocked all of his hits. "Why do you look like me?" Rob question as he jumped away from a kick.

"Why do you look like _me!_ Is the real question!"

Dick looked around to try and piece things together. Batman said something about a portal. And how did that Slade guy look like Deathstroke? "Are you from a different Earth?" Wally-who was running from a large green T-Rex- gasped "The multiple Earths theory! Of course! That other Robin there is your doppelganger!" the redhead quickly said, a top of the dinosaur now.

"Aren't doppelgangers supposed to be like the complete opposite?" Conner questioned watching as M'gann and Starfire flew into the air and began to fight. Wally shook his head, getting up from being thrown to the ground. "Nope! I mean unless they are villains, then we aren't the _complete_ opposite."

"Eit eht xer-t segl!" Zatanna chanted and the dinosaur's legs were tied with rope, causing the green beast to fall to the ground and changed back into Beastboy, who was tied up on the ground, thinking of what to change into the break the ropes. "Titans stop!" Robin ordered as Beastboy changed into a rhino, breaking the roped easily and Starfire descended to the ground and the two went to Robin.

Rob held a hand up to stop the others from attacking. He turned Zatanna and pointed at them before nodding. "Ffucdnah meht!" she chanted and handcuffs appeared on their hands. Conner and Wally went behind them as the rest lead them to the cave.

"Don't break out of them, it'll make us betray their trust even more," Robin ordered Beastboy and Starfire stayed silent and just nodded.

* * *

Collars were put on both Star and Beastboy. Both raising an eyebrow as their handcuffs were taken off. "What are these things?" the green boy questioned panicking.  
"Inhibitor collars, you aren't able to use your powers with them on," Rob answered as Wally took Robin's belt off. "If he's anything like you, Rob then we might want to put this somewhere." Rob nodded and handed the belt over to Artemis as M'gann set the mindlink up. **(Italic's with ' before/after is mindlink)**

 _'Remember when the Red's attacked?'_

 _'How could I forget?'_

 _'Put this in the hideout in the library.'_

Artemis nodded and ran off with the belt gripped tightly in her hands. "The league should be here any minute, I've informed them of what happened," Zatanna stated Conner tensed "Can't we handle them ourselves?"

"We don't know what will happen." Wally defended quickly "We need to...we need to make sure they tell the truth, and the league only has the right tech for that." Wally whispered so the three of them wouldn't hear.

"What will they do to us?" Beastboy asked trying to get out of the collar they put on his neck. "Yes, it was not the best of ideas to just let them take us, Robin," Starfire said and Robin shook his head. "There's where your wrong Star, they might be able to take us back home!" he quickly said writhing his hands as if it would get the handcuffs off of him.

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 **Do you like it? Sorry, it was a bit rushed! If you have any requests for what should happen in later chapters tell me!**

 **Please review! It makes my day!**


	2. Chapter 2

**Thank you for all the follows/favorites!**

 **Disclaimer: I own nothing!**

 _ **Author's P.O.V.**_

 _"The league should be here any minute, I've informed them of what happened," Zatanna stated Conner tensed "Can't we handle them ourselves?"_

 _"We don't know what will happen." Wally defended quickly "We need to...we need to make sure they tell the truth, and the league only has the right tech for that." Wally whispered so the three of them wouldn't hear._

 _"What will they do to us?" Beastboy asked trying to get out of the collar they put on his neck. "Yes, it was not the best of ideas to just let them take us, Robin," Starfire said and Robin shook his head. "There's where your wrong Star, they might be able to take us back home!" he quickly said writhing his hands as if it would get the handcuffs off of him._

"The league thing won't work Zee, Bats said they were on an off-world mission for the next few days." Conner visibly relaxed, while Wally pointed to the three people they had captured. "What are we going to do with them?" As Rob went over a few scenarios, M'gann studied them. The girl clearly had superhuman strength and flight. She also had heat vision. Was she a Kryptonian? Like Superman? She had the powers. Though her eyes were all bright green, Superman nor the new Kryptonian, Supergirl had that.

The green boy had the powers to turn into any animal he wanted. He seemed to be the youngest out of the three and the most carefree. He had a spiky tooth and had been asking for Tofu? Huh, the martian never recalled hearing of that food before. While the other Robin didn't have the tech that their's did. He was much taller and had brighter clothing. And his hair was spiked.

She still couldn't get the idea about that multiple Earths theory Wally keeps talking about. It was weird, sure there was Mars and other aliens out there but another Earth? With their doppelgangers? Was there a version of her on their Earth too?

Artemis ran back in, eyeing the three captives. Looking at them up and down. "We need to do something about them." She stated gesturing to the three and Beastboy inwardly cringed. "We've got names you know." he pointed out, the team looked at him and then looked back at each other. "Mind sharing them with us?" Rob questioned raising an eyebrow at them.

"I am Starfire! Or Kor'i!" **(Please tell me I did her name right! If I did not please correct me!)** the redhead said proudly and looked over at Robin, her eyes lingering before looking back at the team. "I'm Beastboy." the green boy said looking back at the kitchen, stopping himself from asking for tofu. "I'm Robin."

"No, he's Robin." Zatanna started quickly, taking a step forward, but Rob put a hand on her shoulder and gently pulled her back. He looked at the three and put his hands behind his back, joining them together. "Why are you here?"

"We don't need to tell you th-"

"We were fighting a villain, Slade, and a portal opened and before we know it, we're here," Robin explained, as he stepped in front of Beastboy, cutting him off. "Wherever this is anyways," he added quietly still writhing his hands uncomfortably in the cuffs. "Why should we trust them?" Conner questioned, crossing his arms and glaring them down.

"Why shouldn't we? I mean, you can't just make something like that up." M'gann countered and Conner looked at her with surprise, before looking at the team and seeing their noticeable, slight pain on their faces. "Did you...did you read their minds?" he asked, unsure and the room fell silent. M'gann slowly nodded. "They're telling the truth," she confirmed, nervous and Wally ran a hand through his hair. "You're only supposed to read villains minds!" he angrily said, clenching his fist.

"I didn't know they weren't villains..." the martian slowly said, grabbing her forearm and stepping backward. "We don't need to worry about this now." Rob almost yelled out, before Wally could say another thing back to her. "Kid, maybe you should go cool off," he suggested his brows slightly furrowing in thought. Wally, seeing this as more of a command, nodded and left the room.

Dick approached them slowly "Try anything and these get right back on you." he warned, slightly bearing his teeth. They just simply nodded as he removed their collars and Robins handcuffs. "You want any...water?" he slowly questioned and all but Robin nodded as if he had seen right through the others trick into getting a tracker.

"If you even think about leaving, you're done." Artemis menacingly started, jabbing a finger into Beastboys chest as she followed Robin to the kitchen, looking back to Conner and M'gann, silently asking them to stay and watch while Zatanna followed her.

* * *

"How are we gonna leave?" Beastboy asked, rubbing his neck from the newfound freedom. "We won't, they will help us get home." Robin confidently said, looking back to Superboy and Miss Martian as they talked, paying no attention to the three. "We should not rely on them Robin what if they-"

"They won't Star, I promise." he comforted, putting a hand on her shoulder and giving her a small smile. "You haven't kept all of your promises Robin." she looked down, closing her eyes tightly and his lips thinned as he nodded. "No, your right. If they don't help us I'll find us a way out of here. And if I don't then Raven and Cy will get us back home." Robin reassured, looking back at Beastboy who then gave him a thumbs up.

"I got your waters," Rob said, jumping over to them and handing the three of them a water. "I said no." Robin reminded while Rob shrugged and gave his usual smirk "You never know, if you change your mind, it's right there." Robin simply nodded and set the cup down on the table while his two teammates gulped the refreshing drink down. Robin couldn't lie, his mouth was as dry as a desert. He just couldn't trust this team.

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 **Hoped that this one was a bit better! If you have any ideas for later chapters tell me!**

 **Please review! It makes my day!**


	3. Chapter 3

**Thank you all for the Favorites and Follows! (OH, MY GOD THERE'S SO MANY FOR JUST TWO CHAPTERS!) I update slowly and have really bad writing skills, I don't deserve you guys!**

 **Disclaimer: I don't own anything!**

 _ **Author's P.O.V.**_

Wally jumped onto the couch and went to find the remote when he didn't see it he concluded that, like usual, Conner had it. Instead, the green boy who called himself Beastboy was flipping through the channels with confusion, constantly grumbling something to himself. While Starfire and Robin sat next to him talking to one another. The redheaded speedster let out a low, quiet groan and stood up, walking toward the kitchen to find most of his team looking at the three. "Didn't think we had a problem till they took over the place." M'gann slowly said looking around the kitchen. "My friends, they probably did not mean to, maybe this is how most act on their Earth?"

"I never want to go there..." Wally stated, there were pizza boxes laying on the floor in front of them, yes he did eat a lot but at least he had the decency to pick up after himself. "The pizza here is so much better! Cy would've loved it!" Robin grumbled something at the comment and stood up, picking the boxes and making his way to the trash. "Of course, the most immature guy on our team is mature on that Earth." Artemis laughed at Wally's statement and shook her head, covering her mouth as she did so. "You think Rob is the most immature member? Wow..."

All heads turned as the zeta tubes announced Black Canary. "Ready for training?" Rob walked out of his room with narrowed eyes. "You don't even look at our doppelgangers?" he questioned, walking up to the leaguer. "Not anything new to me, besides, they'll be training with us today." She said those things as if they were no big deal. The three doppelgangers stood from the couches and approached Dinah, before looking at the seven team members.

As they walked to the training room Starfire and Beastboy looked at the cave in awe. Of course, Titans Tower was large, but it definitely wasn't this big, not by a long shot. Robin and Rob were studying their opponents, trying to find anywhere that would be a weak point. "First up is Conner and-" she pointed to Beastboy who stated his name and went up to the platform standing across from Conner. He instantly turned into a cheetah and ran around his opponent.

Conner-who was clearly done with everyone's shit-held his arms out and the green cheetah hit it. Phased for only a moment, Beastboy turned into a gorilla and Conner let out a growl. "I hate monkeys," he mumbled and jumped forward, pulling his fist back to punch him only to have it caught by the gorilla, who's plan backfired and fell to the ground. Beastboy narrowed his eyes and turned into a T-Rex. Engulfing Conner in his teeth and shaking him back and forth. The half-Kryptonian gripped the dinosaur's jaw and pushed on it, forcing it to open and let him out, once his plan had succeeded he ran to the legs and pushed him down to hit the ground once more, telling the room that Beastboy had failed.

"Okay, Zatanna and uh...Starfire?" the two walked up to the platform, one clearly more confident than the other. Starfire tried to track Zatanna's path to get a direct attack on her. She flew up into the air and Zatanna's hand went on her hips. "Two can play at that game. Etativel!" she flew up into the air, across from Starfire. Kor'i shot her beams at the magician who just barely blocked them.

"Dnal" Zatanna loudly stated and the two of them fell to the ground, confused Starfire looked at her body, what had happened? Another beam was shot and this time she didn't miss. The raven-haired-girl fell to the floor, the only thing moving was her chest. Starfire flew to her and picked the girl up, bringing her to the air by the collar of her shirt. Pulling her fist back, Kor'i was hit by something and soon standing on the ground once again, dropping her opponent. Rubbing her head she noticed a Batarang on the floor, and Rob holding Zatanna.

"Star what was that?" Robin asked frustrated and Rob had disappeared. "I thought we were fighting..." she began, a bit scared she had not seen him this angry at only her before. "No, this was training! We don't-"

"Stop!" all attention was back on Black Canary. "That's enough training for now. Work out your problems, and if you need me, I'll be here." her voice went from demanding to calm and caring in a millisecond. Robin rolled his shoulder and a loud crack came out of it. Rob walked back into the room, glaring at Starfire with his arms crossed. As they walked back to the main room, the three doppelgangers kept their distance. "We can't gain their trust by nearly killing one of their team members!We'll never get home!" Robin lectured as Starfire kept her head down, guilt crossing all her features. He sighed and looked at Beastboy who shrugged before furrowing his brows. "It's okay Star, none of 'em are judging you, they are just worried about their friend." Beastboy began with a smile on his face and hand on her shoulder. "We would be doing the same thing if that happened to one of us, right?" Starfire merely nodded, still guilt-stricken.

The three of them had their own rooms in the Cave. Though Rob found it hard to sleep, he and Zatanna would always have these Midnight talks when one of them weren't able to sleep. She had woke up a while ago but soon found it easier to fall asleep. He didn't mind at all, by any means but he was just worried, so many insane possibilities were going through his mind.

' _What if that blast was poisonous?'_

 _'What if she did die? And he's just in denial?'_

 _'What if this is all a dream and when he wakes up they wouldn't even be together?'_

"Still up?" he turned on his heels to see Robin, with a cup of coffee in his hand. Rob shrugged and looked toward the direction of the medbay. "You shouldn't worry, your friend is fine, she doesn't even need the medical attention," he said, taking a drink of the coffee. Rob just hummed and ran a hand through his disheveled hair. He arched his back as a random shiver ran down his spine, and let out a loud yawn. "You never know..." Rob dragged as if hinting something to his doppelganger. Robin shrugged and began to walk to his room.

"Thanks." he disappeared. Rob wrinkled his nose. "That is kind of annoying." he sighed

* * *

 **Sorry it took me so long! This chapter is last minute! Hope you liked it!**

 **Please review! It makes my day!**


	4. Chapter 4

**It's been a while! So I was thinking of making a story where the team goes undercover at a High School. Would you guys want to read that?**

 **Disclaimer: I own nothing**

 _ **Author's P.O.V**_

They were all on a mission, it wasn't their idea, the Teen Titans would've happily stayed at the cave. They were unfamiliar to the covert-ops missions that they had. Not being in the spotlight, or being praised afterwards. It was weird. Then there was the mind-link. It was efficient, but hurt in the beginning, and took them awhile to not think about...certain things.

It was in a warehouse, many hostages tied up against the walls. Bombs next to them. One of the captures tauntingly held up a remote. "One press of this button, and they'll all die. Kid Flash ran over and grabbed the remote in the blink of an eye. The redhead smiled and held it up in the air, only to be tackled by one of the men, easily dropping the remote.

 _'KF! You're better than this!'_

Beast Boy turned into a cheetah and ran toward the remote after seeing everyone was busy either trying to cut the ropes or fighting. His head turned and he saw a portal open. He heard them. Cyborg and Raven! The portal was closing quickly, the green animal ran toward the portal, he felt the security of his home, he was so close.

He jumped, but was pushed out of the way as the building began to blow up. Realization kicked in as he looked around, seeing Zatanna try to cast a spell, only to just be grabbed by Superboy, like the rest of them and be sheltered by him. It happened in almost slow motion. The screams of all of those innocent people. M'gann passing out from the heat, being one of the closest to the bomb as it exploded.

* * *

"What were you thinking!" Garfield didn't say anything. Just looked down at his feet. "The portal! It opened! It was to go back home!" He could _feel_ their glares. "That's not an excuse!" Conner cut into Robins lectures. "All of those people died from your selflessness!" Robin stated, jabbing a finger into his chest. He looked around the room.

"I could've put a forcefield around them! They might've been saved." Zatanna said, her head in her hands. Artemis put a hand on her shoulder and looked back at Beast Boy. "We _all_ could have done something." Rob looked emotionless. Behind his shades you would've seen the dullness in his eyes. Sure, he witnessed a lot of death. This time? It was different. In Gotham people died left and right. Much of it wasn't possible to avoid. Though, this time, just one step of Beast Boy could've saved all of those lives.

Starfire sat on the couch, she felt different. It was one of the first times she's experienced people dying on a mission. "If any of you need to talk, you know where I'll be." Black Canary said thoughtfully, worry in her eyes as she looked at the team still trying to cope.

"I know I messed up I just, I miss _home_ , and I know it's no excuse, and I mean, on our Earth they don't-usually go that far. " Conner stood and mumbled something under his breath before walking out of the main room. "Just...go to the showers." Rob stated, ignoring the Teen Titans leader as he tried to discipline his teammate.

Wally sat there, staying quiet. It wasn't the first time a mission ended in death. It didn't hit their team as hard as it did the Teen Titans. It would always be quiet for awhile. Aqualad lecturing them, saying it wasn't their fault, they couldn't do anything. But this time, Kaldur was quiet too, staring at Beast Boy, wanting to say something to the boy.

* * *

 _ **The Next Day**_

Beast Boy still seemed a bit, shaken, after last night's events. Rob entered the cave while typing something on his glove computer. "Last night, a portal opened in that warehouse, supposedly it was to your guys earth. Now, if I'm correct, none of those guys had anything that could make a portal." The Teen Titans were all closely listening. While the others just raised their eyebrows. "Something-or someone did, I looked back at the footage, that their camera took, and if you look up there-" he cut himself off, showing everyone footage of the other night, before pausing and zooming up on a figure.

"It must be Slade! He was the one that brought us here!" Robin stated, his arm tensing up as he mentioned the villain. "Why would he put it there so you all could get to it?" Wally questioned, leaning up against the doorway.

"He-I don't know. But, he has a way to get us home, and we need to get it back." The Team-excluding the Teen Titans-were clearly having a mental conversation, about what was going on.

"We need to figure out his next move."

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 **That was short, but I felt like I really needed to update before you guys thought I abandoned this story.**

 **Please Review!**


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